sys/netinet/ip_icmp.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)ip_icmp.c   8.2 (Berkeley) 1/4/94
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include "opt_inet.h"
  36 #include "opt_ipsec.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/mbuf.h>
  41 #include <sys/protosw.h>
  42 #include <sys/socket.h>
  43 #include <sys/time.h>
  44 #include <sys/kernel.h>
  45 #include <sys/sysctl.h>
  46 #include <sys/syslog.h>
  47
  48 #include <net/if.h>
  49 #include <net/if_types.h>
  50 #include <net/route.h>
  51 #include <net/vnet.h>
  52
  53 #include <netinet/in.h>
  54 #include <netinet/in_pcb.h>
  55 #include <netinet/in_systm.h>
  56 #include <netinet/in_var.h>
  57 #include <netinet/ip.h>
  58 #include <netinet/ip_icmp.h>
  59 #include <netinet/ip_var.h>
  60 #include <netinet/ip_options.h>
  61 #include <netinet/tcp.h>
  62 #include <netinet/tcp_var.h>
  63 #include <netinet/tcpip.h>
  64 #include <netinet/icmp_var.h>
  65
  66 #ifdef INET
  67 #ifdef IPSEC
  68 #include <netipsec/ipsec.h>
  69 #include <netipsec/key.h>
  70 #endif
  71
  72 #include <machine/in_cksum.h>
  73
  74 #include <security/mac/mac_framework.h>
  75 #endif /* INET */
  76
  77 /*
  78  * ICMP routines: error generation, receive packet processing, and
  79  * routines to turnaround packets back to the originator, and
  80  * host table maintenance routines.
  81  */
  82 static VNET_DEFINE(int, icmplim) = 200;
  83 #define V_icmplim                       VNET(icmplim)
  84 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
  85         &VNET_NAME(icmplim), 0,
  86         "Maximum number of ICMP responses per second");
  87
  88 static VNET_DEFINE(int, icmplim_output) = 1;
  89 #define V_icmplim_output                VNET(icmplim_output)
  90 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW,
  91         &VNET_NAME(icmplim_output), 0,
  92         "Enable rate limiting of ICMP responses");
  93
  94 #ifdef INET
  95 VNET_DEFINE(struct icmpstat, icmpstat);
  96 SYSCTL_VNET_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW,
  97         &VNET_NAME(icmpstat), icmpstat, "");
  98
  99 static VNET_DEFINE(int, icmpmaskrepl) = 0;
 100 #define V_icmpmaskrepl                  VNET(icmpmaskrepl)
 101 SYSCTL_VNET_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
 102         &VNET_NAME(icmpmaskrepl), 0,
 103         "Reply to ICMP Address Mask Request packets.");
 104
 105 static VNET_DEFINE(u_int, icmpmaskfake) = 0;
 106 #define V_icmpmaskfake                  VNET(icmpmaskfake)
 107 SYSCTL_VNET_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW,
 108         &VNET_NAME(icmpmaskfake), 0,
 109         "Fake reply to ICMP Address Mask Request packets.");
 110
 111 VNET_DEFINE(int, drop_redirect) = 0;
 112
 113 static VNET_DEFINE(int, log_redirect) = 0;
 114 #define V_log_redirect                  VNET(log_redirect)
 115 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
 116         &VNET_NAME(log_redirect), 0,
 117         "Log ICMP redirects to the console");
 118
 119 static VNET_DEFINE(char, reply_src[IFNAMSIZ]);
 120 #define V_reply_src                     VNET(reply_src)
 121 SYSCTL_VNET_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW,
 122         &VNET_NAME(reply_src), IFNAMSIZ,
 123         "icmp reply source for non-local packets.");
 124
 125 static VNET_DEFINE(int, icmp_rfi) = 0;
 126 #define V_icmp_rfi                      VNET(icmp_rfi)
 127 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW,
 128         &VNET_NAME(icmp_rfi), 0,
 129         "ICMP reply from incoming interface for non-local packets");
 130
 131 static VNET_DEFINE(int, icmp_quotelen) = 8;
 132 #define V_icmp_quotelen                 VNET(icmp_quotelen)
 133 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW,
 134         &VNET_NAME(icmp_quotelen), 0,
 135         "Number of bytes from original packet to quote in ICMP reply");
 136
 137 /*
 138  * ICMP broadcast echo sysctl
 139  */
 140 static VNET_DEFINE(int, icmpbmcastecho) = 0;
 141 #define V_icmpbmcastecho                VNET(icmpbmcastecho)
 142 SYSCTL_VNET_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
 143         &VNET_NAME(icmpbmcastecho), 0,
 144         "");
 145
 146
 147 #ifdef ICMPPRINTFS
 148 int     icmpprintfs = 0;
 149 #endif
 150
 151 static void     icmp_reflect(struct mbuf *);
 152 static void     icmp_send(struct mbuf *, struct mbuf *);
 153
 154 extern  struct protosw inetsw[];
 155
 156 static int
 157 sysctl_net_icmp_drop_redir(SYSCTL_HANDLER_ARGS)
 158 {
 159         int error, new;
 160         int i;
 161         struct radix_node_head *rnh;
 162
 163         new = V_drop_redirect;
 164         error = sysctl_handle_int(oidp, &new, 0, req);
 165         if (error == 0 && req->newptr) {
 166                 new = (new != 0) ? 1 : 0;
 167
 168                 if (new == V_drop_redirect)
 169                         return (0);
 170
 171                 for (i = 0; i < rt_numfibs; i++) {
 172                         if ((rnh = rt_tables_get_rnh(i, AF_INET)) == NULL)
 173                                 continue;
 174                         RADIX_NODE_HEAD_LOCK(rnh);
 175                         in_setmatchfunc(rnh, new);
 176                         RADIX_NODE_HEAD_UNLOCK(rnh);
 177                 }
 178
 179                 V_drop_redirect = new;
 180         }
 181
 182         return (error);
 183 }
 184
 185 SYSCTL_VNET_PROC(_net_inet_icmp, OID_AUTO, drop_redirect,
 186     CTLTYPE_INT|CTLFLAG_RW, 0, 0,
 187     sysctl_net_icmp_drop_redir, "I", "Ignore ICMP redirects");
 188
 189 /*
 190  * Kernel module interface for updating icmpstat.  The argument is an index
 191  * into icmpstat treated as an array of u_long.  While this encodes the
 192  * general layout of icmpstat into the caller, it doesn't encode its
 193  * location, so that future changes to add, for example, per-CPU stats
 194  * support won't cause binary compatibility problems for kernel modules.
 195  */
 196 void
 197 kmod_icmpstat_inc(int statnum)
 198 {
 199
 200         (*((u_long *)&V_icmpstat + statnum))++;
 201 }
 202
 203 /*
 204  * Generate an error packet of type error
 205  * in response to bad packet ip.
 206  */
 207 void
 208 icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
 209 {
 210         register struct ip *oip = mtod(n, struct ip *), *nip;
 211         register unsigned oiphlen = oip->ip_hl << 2;
 212         register struct icmp *icp;
 213         register struct mbuf *m;
 214         unsigned icmplen, icmpelen, nlen;
 215
 216         KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__));
 217 #ifdef ICMPPRINTFS
 218         if (icmpprintfs)
 219                 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
 220 #endif
 221         if (type != ICMP_REDIRECT)
 222                 ICMPSTAT_INC(icps_error);
 223         /*
 224          * Don't send error:
 225          *  if the original packet was encrypted.
 226          *  if not the first fragment of message.
 227          *  in response to a multicast or broadcast packet.
 228          *  if the old packet protocol was an ICMP error message.
 229          */
 230         if (n->m_flags & M_DECRYPTED)
 231                 goto freeit;
 232         if (oip->ip_off & ~(IP_MF|IP_DF))
 233                 goto freeit;
 234         if (n->m_flags & (M_BCAST|M_MCAST))
 235                 goto freeit;
 236         if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
 237           n->m_len >= oiphlen + ICMP_MINLEN &&
 238           !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) {
 239                 ICMPSTAT_INC(icps_oldicmp);
 240                 goto freeit;
 241         }
 242         /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */
 243         if (oiphlen + 8 > n->m_len)
 244                 goto freeit;
 245         /*
 246          * Calculate length to quote from original packet and
 247          * prevent the ICMP mbuf from overflowing.
 248          * Unfortunatly this is non-trivial since ip_forward()
 249          * sends us truncated packets.
 250          */
 251         nlen = m_length(n, NULL);
 252         if (oip->ip_p == IPPROTO_TCP) {
 253                 struct tcphdr *th;
 254                 int tcphlen;
 255
 256                 if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
 257                     n->m_next == NULL)
 258                         goto stdreply;
 259                 if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
 260                     ((n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL))
 261                         goto freeit;
 262                 th = (struct tcphdr *)((caddr_t)oip + oiphlen);
 263                 tcphlen = th->th_off << 2;
 264                 if (tcphlen < sizeof(struct tcphdr))
 265                         goto freeit;
 266                 if (oip->ip_len < oiphlen + tcphlen)
 267                         goto freeit;
 268                 if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
 269                         goto stdreply;
 270                 if (n->m_len < oiphlen + tcphlen &&
 271                     ((n = m_pullup(n, oiphlen + tcphlen)) == NULL))
 272                         goto freeit;
 273                 icmpelen = max(tcphlen, min(V_icmp_quotelen, oip->ip_len - oiphlen));
 274         } else
 275 stdreply:       icmpelen = max(8, min(V_icmp_quotelen, oip->ip_len - oiphlen));
 276
 277         icmplen = min(oiphlen + icmpelen, nlen);
 278         if (icmplen < sizeof(struct ip))
 279                 goto freeit;
 280
 281         if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
 282                 m = m_gethdr(M_DONTWAIT, MT_DATA);
 283         else
 284                 m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
 285         if (m == NULL)
 286                 goto freeit;
 287 #ifdef MAC
 288         mac_netinet_icmp_reply(n, m);
 289 #endif
 290         icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN);
 291         m_align(m, ICMP_MINLEN + icmplen);
 292         m->m_len = ICMP_MINLEN + icmplen;
 293
 294         /* XXX MRT  make the outgoing packet use the same FIB
 295          * that was associated with the incoming packet
 296          */
 297         M_SETFIB(m, M_GETFIB(n));
 298         icp = mtod(m, struct icmp *);
 299         ICMPSTAT_INC(icps_outhist[type]);
 300         icp->icmp_type = type;
 301         if (type == ICMP_REDIRECT)
 302                 icp->icmp_gwaddr.s_addr = dest;
 303         else {
 304                 icp->icmp_void = 0;
 305                 /*
 306                  * The following assignments assume an overlay with the
 307                  * just zeroed icmp_void field.
 308                  */
 309                 if (type == ICMP_PARAMPROB) {
 310                         icp->icmp_pptr = code;
 311                         code = 0;
 312                 } else if (type == ICMP_UNREACH &&
 313                         code == ICMP_UNREACH_NEEDFRAG && mtu) {
 314                         icp->icmp_nextmtu = htons(mtu);
 315                 }
 316         }
 317         icp->icmp_code = code;
 318
 319         /*
 320          * Copy the quotation into ICMP message and
 321          * convert quoted IP header back to network representation.
 322          */
 323         m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
 324         nip = &icp->icmp_ip;
 325         nip->ip_len = htons(nip->ip_len);
 326         nip->ip_off = htons(nip->ip_off);
 327
 328         /*
 329          * Set up ICMP message mbuf and copy old IP header (without options
 330          * in front of ICMP message.
 331          * If the original mbuf was meant to bypass the firewall, the error
 332          * reply should bypass as well.
 333          */
 334         m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
 335         m->m_data -= sizeof(struct ip);
 336         m->m_len += sizeof(struct ip);
 337         m->m_pkthdr.len = m->m_len;
 338         m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
 339         nip = mtod(m, struct ip *);
 340         bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
 341         nip->ip_len = m->m_len;
 342         nip->ip_v = IPVERSION;
 343         nip->ip_hl = 5;
 344         nip->ip_p = IPPROTO_ICMP;
 345         nip->ip_tos = 0;
 346         icmp_reflect(m);
 347
 348 freeit:
 349         m_freem(n);
 350 }
 351
 352 /*
 353  * Process a received ICMP message.
 354  */
 355 void
 356 icmp_input(struct mbuf *m, int off)
 357 {
 358         struct icmp *icp;
 359         struct in_ifaddr *ia;
 360         struct ip *ip = mtod(m, struct ip *);
 361         struct sockaddr_in icmpsrc, icmpdst, icmpgw;
 362         int hlen = off;
 363         int icmplen = ip->ip_len;
 364         int i, code;
 365         void (*ctlfunc)(int, struct sockaddr *, void *);
 366         int fibnum;
 367
 368         /*
 369          * Locate icmp structure in mbuf, and check
 370          * that not corrupted and of at least minimum length.
 371          */
 372 #ifdef ICMPPRINTFS
 373         if (icmpprintfs) {
 374                 char buf[4 * sizeof "123"];
 375                 strcpy(buf, inet_ntoa(ip->ip_src));
 376                 printf("icmp_input from %s to %s, len %d\n",
 377                        buf, inet_ntoa(ip->ip_dst), icmplen);
 378         }
 379 #endif
 380         if (icmplen < ICMP_MINLEN) {
 381                 ICMPSTAT_INC(icps_tooshort);
 382                 goto freeit;
 383         }
 384         i = hlen + min(icmplen, ICMP_ADVLENMIN);
 385         if (m->m_len < i && (m = m_pullup(m, i)) == NULL)  {
 386                 ICMPSTAT_INC(icps_tooshort);
 387                 return;
 388         }
 389         ip = mtod(m, struct ip *);
 390         m->m_len -= hlen;
 391         m->m_data += hlen;
 392         icp = mtod(m, struct icmp *);
 393         if (in_cksum(m, icmplen)) {
 394                 ICMPSTAT_INC(icps_checksum);
 395                 goto freeit;
 396         }
 397         m->m_len += hlen;
 398         m->m_data -= hlen;
 399
 400         if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
 401                 /*
 402                  * Deliver very specific ICMP type only.
 403                  */
 404                 switch (icp->icmp_type) {
 405                 case ICMP_UNREACH:
 406                 case ICMP_TIMXCEED:
 407                         break;
 408                 default:
 409                         goto freeit;
 410                 }
 411         }
 412
 413 #ifdef ICMPPRINTFS
 414         if (icmpprintfs)
 415                 printf("icmp_input, type %d code %d\n", icp->icmp_type,
 416                     icp->icmp_code);
 417 #endif
 418
 419         /*
 420          * Message type specific processing.
 421          */
 422         if (icp->icmp_type > ICMP_MAXTYPE)
 423                 goto raw;
 424
 425         /* Initialize */
 426         bzero(&icmpsrc, sizeof(icmpsrc));
 427         icmpsrc.sin_len = sizeof(struct sockaddr_in);
 428         icmpsrc.sin_family = AF_INET;
 429         bzero(&icmpdst, sizeof(icmpdst));
 430         icmpdst.sin_len = sizeof(struct sockaddr_in);
 431         icmpdst.sin_family = AF_INET;
 432         bzero(&icmpgw, sizeof(icmpgw));
 433         icmpgw.sin_len = sizeof(struct sockaddr_in);
 434         icmpgw.sin_family = AF_INET;
 435
 436         ICMPSTAT_INC(icps_inhist[icp->icmp_type]);
 437         code = icp->icmp_code;
 438         switch (icp->icmp_type) {
 439
 440         case ICMP_UNREACH:
 441                 switch (code) {
 442                         case ICMP_UNREACH_NET:
 443                         case ICMP_UNREACH_HOST:
 444                         case ICMP_UNREACH_SRCFAIL:
 445                         case ICMP_UNREACH_NET_UNKNOWN:
 446                         case ICMP_UNREACH_HOST_UNKNOWN:
 447                         case ICMP_UNREACH_ISOLATED:
 448                         case ICMP_UNREACH_TOSNET:
 449                         case ICMP_UNREACH_TOSHOST:
 450                         case ICMP_UNREACH_HOST_PRECEDENCE:
 451                         case ICMP_UNREACH_PRECEDENCE_CUTOFF:
 452                                 code = PRC_UNREACH_NET;
 453                                 break;
 454
 455                         case ICMP_UNREACH_NEEDFRAG:
 456                                 code = PRC_MSGSIZE;
 457                                 break;
 458
 459                         /*
 460                          * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
 461                          * Treat subcodes 2,3 as immediate RST
 462                          */
 463                         case ICMP_UNREACH_PROTOCOL:
 464                         case ICMP_UNREACH_PORT:
 465                                 code = PRC_UNREACH_PORT;
 466                                 break;
 467
 468                         case ICMP_UNREACH_NET_PROHIB:
 469                         case ICMP_UNREACH_HOST_PROHIB:
 470                         case ICMP_UNREACH_FILTER_PROHIB:
 471                                 code = PRC_UNREACH_ADMIN_PROHIB;
 472                                 break;
 473
 474                         default:
 475                                 goto badcode;
 476                 }
 477                 goto deliver;
 478
 479         case ICMP_TIMXCEED:
 480                 if (code > 1)
 481                         goto badcode;
 482                 code += PRC_TIMXCEED_INTRANS;
 483                 goto deliver;
 484
 485         case ICMP_PARAMPROB:
 486                 if (code > 1)
 487                         goto badcode;
 488                 code = PRC_PARAMPROB;
 489                 goto deliver;
 490
 491         case ICMP_SOURCEQUENCH:
 492                 if (code)
 493                         goto badcode;
 494                 code = PRC_QUENCH;
 495         deliver:
 496                 /*
 497                  * Problem with datagram; advise higher level routines.
 498                  */
 499                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
 500                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
 501                         ICMPSTAT_INC(icps_badlen);
 502                         goto freeit;
 503                 }
 504                 icp->icmp_ip.ip_len = ntohs(icp->icmp_ip.ip_len);
 505                 /* Discard ICMP's in response to multicast packets */
 506                 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
 507                         goto badcode;
 508 #ifdef ICMPPRINTFS
 509                 if (icmpprintfs)
 510                         printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
 511 #endif
 512                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
 513                 /*
 514                  * XXX if the packet contains [IPv4 AH TCP], we can't make a
 515                  * notification to TCP layer.
 516                  */
 517                 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
 518                 if (ctlfunc)
 519                         (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
 520                                    (void *)&icp->icmp_ip);
 521                 break;
 522
 523         badcode:
 524                 ICMPSTAT_INC(icps_badcode);
 525                 break;
 526
 527         case ICMP_ECHO:
 528                 if (!V_icmpbmcastecho
 529                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
 530                         ICMPSTAT_INC(icps_bmcastecho);
 531                         break;
 532                 }
 533                 icp->icmp_type = ICMP_ECHOREPLY;
 534                 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
 535                         goto freeit;
 536                 else
 537                         goto reflect;
 538
 539         case ICMP_TSTAMP:
 540                 if (!V_icmpbmcastecho
 541                     && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
 542                         ICMPSTAT_INC(icps_bmcasttstamp);
 543                         break;
 544                 }
 545                 if (icmplen < ICMP_TSLEN) {
 546                         ICMPSTAT_INC(icps_badlen);
 547                         break;
 548                 }
 549                 icp->icmp_type = ICMP_TSTAMPREPLY;
 550                 icp->icmp_rtime = iptime();
 551                 icp->icmp_ttime = icp->icmp_rtime;      /* bogus, do later! */
 552                 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
 553                         goto freeit;
 554                 else
 555                         goto reflect;
 556
 557         case ICMP_MASKREQ:
 558                 if (V_icmpmaskrepl == 0)
 559                         break;
 560                 /*
 561                  * We are not able to respond with all ones broadcast
 562                  * unless we receive it over a point-to-point interface.
 563                  */
 564                 if (icmplen < ICMP_MASKLEN)
 565                         break;
 566                 switch (ip->ip_dst.s_addr) {
 567
 568                 case INADDR_BROADCAST:
 569                 case INADDR_ANY:
 570                         icmpdst.sin_addr = ip->ip_src;
 571                         break;
 572
 573                 default:
 574                         icmpdst.sin_addr = ip->ip_dst;
 575                 }
 576                 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
 577                             (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
 578                 if (ia == NULL)
 579                         break;
 580                 if (ia->ia_ifp == NULL) {
 581                         ifa_free(&ia->ia_ifa);
 582                         break;
 583                 }
 584                 icp->icmp_type = ICMP_MASKREPLY;
 585                 if (V_icmpmaskfake == 0)
 586                         icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
 587                 else
 588                         icp->icmp_mask = V_icmpmaskfake;
 589                 if (ip->ip_src.s_addr == 0) {
 590                         if (ia->ia_ifp->if_flags & IFF_BROADCAST)
 591                             ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
 592                         else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
 593                             ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
 594                 }
 595                 ifa_free(&ia->ia_ifa);
 596 reflect:
 597                 ip->ip_len += hlen;     /* since ip_input deducts this */
 598                 ICMPSTAT_INC(icps_reflect);
 599                 ICMPSTAT_INC(icps_outhist[icp->icmp_type]);
 600                 icmp_reflect(m);
 601                 return;
 602
 603         case ICMP_REDIRECT:
 604                 if (V_log_redirect) {
 605                         u_long src, dst, gw;
 606
 607                         src = ntohl(ip->ip_src.s_addr);
 608                         dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
 609                         gw = ntohl(icp->icmp_gwaddr.s_addr);
 610                         printf("icmp redirect from %d.%d.%d.%d: "
 611                                "%d.%d.%d.%d => %d.%d.%d.%d\n",
 612                                (int)(src >> 24), (int)((src >> 16) & 0xff),
 613                                (int)((src >> 8) & 0xff), (int)(src & 0xff),
 614                                (int)(dst >> 24), (int)((dst >> 16) & 0xff),
 615                                (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
 616                                (int)(gw >> 24), (int)((gw >> 16) & 0xff),
 617                                (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
 618                 }
 619                 /*
 620                  * RFC1812 says we must ignore ICMP redirects if we
 621                  * are acting as router.
 622                  */
 623                 if (V_drop_redirect || V_ipforwarding)
 624                         break;
 625                 if (code > 3)
 626                         goto badcode;
 627                 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
 628                     icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
 629                         ICMPSTAT_INC(icps_badlen);
 630                         break;
 631                 }
 632                 /*
 633                  * Short circuit routing redirects to force
 634                  * immediate change in the kernel's routing
 635                  * tables.  The message is also handed to anyone
 636                  * listening on a raw socket (e.g. the routing
 637                  * daemon for use in updating its tables).
 638                  */
 639                 icmpgw.sin_addr = ip->ip_src;
 640                 icmpdst.sin_addr = icp->icmp_gwaddr;
 641 #ifdef  ICMPPRINTFS
 642                 if (icmpprintfs) {
 643                         char buf[4 * sizeof "123"];
 644                         strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
 645
 646                         printf("redirect dst %s to %s\n",
 647                                buf, inet_ntoa(icp->icmp_gwaddr));
 648                 }
 649 #endif
 650                 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
 651                 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
 652                         in_rtredirect((struct sockaddr *)&icmpsrc,
 653                           (struct sockaddr *)&icmpdst,
 654                           (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
 655                           (struct sockaddr *)&icmpgw, fibnum);
 656                 }
 657                 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
 658 #ifdef IPSEC
 659                 key_sa_routechange((struct sockaddr *)&icmpsrc);
 660 #endif
 661                 break;
 662
 663         /*
 664          * No kernel processing for the following;
 665          * just fall through to send to raw listener.
 666          */
 667         case ICMP_ECHOREPLY:
 668         case ICMP_ROUTERADVERT:
 669         case ICMP_ROUTERSOLICIT:
 670         case ICMP_TSTAMPREPLY:
 671         case ICMP_IREQREPLY:
 672         case ICMP_MASKREPLY:
 673         default:
 674                 break;
 675         }
 676
 677 raw:
 678         rip_input(m, off);
 679         return;
 680
 681 freeit:
 682         m_freem(m);
 683 }
 684
 685 /*
 686  * Reflect the ip packet back to the source
 687  */
 688 static void
 689 icmp_reflect(struct mbuf *m)
 690 {
 691         struct ip *ip = mtod(m, struct ip *);
 692         struct ifaddr *ifa;
 693         struct ifnet *ifp;
 694         struct in_ifaddr *ia;
 695         struct in_addr t;
 696         struct mbuf *opts = 0;
 697         int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
 698
 699         if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
 700             IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) ||
 701             IN_ZERONET(ntohl(ip->ip_src.s_addr)) ) {
 702                 m_freem(m);     /* Bad return address */
 703                 ICMPSTAT_INC(icps_badaddr);
 704                 goto done;      /* Ip_output() will check for broadcast */
 705         }
 706
 707         m_addr_changed(m);
 708
 709         t = ip->ip_dst;
 710         ip->ip_dst = ip->ip_src;
 711
 712         /*
 713          * Source selection for ICMP replies:
 714          *
 715          * If the incoming packet was addressed directly to one of our
 716          * own addresses, use dst as the src for the reply.
 717          */
 718         IN_IFADDR_RLOCK();
 719         LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
 720                 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
 721                         t = IA_SIN(ia)->sin_addr;
 722                         IN_IFADDR_RUNLOCK();
 723                         goto match;
 724                 }
 725         }
 726         IN_IFADDR_RUNLOCK();
 727
 728         /*
 729          * If the incoming packet was addressed to one of our broadcast
 730          * addresses, use the first non-broadcast address which corresponds
 731          * to the incoming interface.
 732          */
 733         ifp = m->m_pkthdr.rcvif;
 734         if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
 735                 IF_ADDR_RLOCK(ifp);
 736                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
 737                         if (ifa->ifa_addr->sa_family != AF_INET)
 738                                 continue;
 739                         ia = ifatoia(ifa);
 740                         if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
 741                             t.s_addr) {
 742                                 t = IA_SIN(ia)->sin_addr;
 743                                 IF_ADDR_RUNLOCK(ifp);
 744                                 goto match;
 745                         }
 746                 }
 747                 IF_ADDR_RUNLOCK(ifp);
 748         }
 749         /*
 750          * If the packet was transiting through us, use the address of
 751          * the interface the packet came through in.  If that interface
 752          * doesn't have a suitable IP address, the normal selection
 753          * criteria apply.
 754          */
 755         if (V_icmp_rfi && ifp != NULL) {
 756                 IF_ADDR_RLOCK(ifp);
 757                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
 758                         if (ifa->ifa_addr->sa_family != AF_INET)
 759                                 continue;
 760                         ia = ifatoia(ifa);
 761                         t = IA_SIN(ia)->sin_addr;
 762                         IF_ADDR_RUNLOCK(ifp);
 763                         goto match;
 764                 }
 765                 IF_ADDR_RUNLOCK(ifp);
 766         }
 767         /*
 768          * If the incoming packet was not addressed directly to us, use
 769          * designated interface for icmp replies specified by sysctl
 770          * net.inet.icmp.reply_src (default not set). Otherwise continue
 771          * with normal source selection.
 772          */
 773         if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
 774                 IF_ADDR_RLOCK(ifp);
 775                 TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
 776                         if (ifa->ifa_addr->sa_family != AF_INET)
 777                                 continue;
 778                         ia = ifatoia(ifa);
 779                         t = IA_SIN(ia)->sin_addr;
 780                         IF_ADDR_RUNLOCK(ifp);
 781                         goto match;
 782                 }
 783                 IF_ADDR_RUNLOCK(ifp);
 784         }
 785         /*
 786          * If the packet was transiting through us, use the address of
 787          * the interface that is the closest to the packet source.
 788          * When we don't have a route back to the packet source, stop here
 789          * and drop the packet.
 790          */
 791         ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
 792         if (ia == NULL) {
 793                 m_freem(m);
 794                 ICMPSTAT_INC(icps_noroute);
 795                 goto done;
 796         }
 797         t = IA_SIN(ia)->sin_addr;
 798         ifa_free(&ia->ia_ifa);
 799 match:
 800 #ifdef MAC
 801         mac_netinet_icmp_replyinplace(m);
 802 #endif
 803         ip->ip_src = t;
 804         ip->ip_ttl = V_ip_defttl;
 805
 806         if (optlen > 0) {
 807                 register u_char *cp;
 808                 int opt, cnt;
 809                 u_int len;
 810
 811                 /*
 812                  * Retrieve any source routing from the incoming packet;
 813                  * add on any record-route or timestamp options.
 814                  */
 815                 cp = (u_char *) (ip + 1);
 816                 if ((opts = ip_srcroute(m)) == 0 &&
 817                     (opts = m_gethdr(M_DONTWAIT, MT_DATA))) {
 818                         opts->m_len = sizeof(struct in_addr);
 819                         mtod(opts, struct in_addr *)->s_addr = 0;
 820                 }
 821                 if (opts) {
 822 #ifdef ICMPPRINTFS
 823                     if (icmpprintfs)
 824                             printf("icmp_reflect optlen %d rt %d => ",
 825                                 optlen, opts->m_len);
 826 #endif
 827                     for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
 828                             opt = cp[IPOPT_OPTVAL];
 829                             if (opt == IPOPT_EOL)
 830                                     break;
 831                             if (opt == IPOPT_NOP)
 832                                     len = 1;
 833                             else {
 834                                     if (cnt < IPOPT_OLEN + sizeof(*cp))
 835                                             break;
 836                                     len = cp[IPOPT_OLEN];
 837                                     if (len < IPOPT_OLEN + sizeof(*cp) ||
 838                                         len > cnt)
 839                                             break;
 840                             }
 841                             /*
 842                              * Should check for overflow, but it "can't happen"
 843                              */
 844                             if (opt == IPOPT_RR || opt == IPOPT_TS ||
 845                                 opt == IPOPT_SECURITY) {
 846                                     bcopy((caddr_t)cp,
 847                                         mtod(opts, caddr_t) + opts->m_len, len);
 848                                     opts->m_len += len;
 849                             }
 850                     }
 851                     /* Terminate & pad, if necessary */
 852                     cnt = opts->m_len % 4;
 853                     if (cnt) {
 854                             for (; cnt < 4; cnt++) {
 855                                     *(mtod(opts, caddr_t) + opts->m_len) =
 856                                         IPOPT_EOL;
 857                                     opts->m_len++;
 858                             }
 859                     }
 860 #ifdef ICMPPRINTFS
 861                     if (icmpprintfs)
 862                             printf("%d\n", opts->m_len);
 863 #endif
 864                 }
 865                 /*
 866                  * Now strip out original options by copying rest of first
 867                  * mbuf's data back, and adjust the IP length.
 868                  */
 869                 ip->ip_len -= optlen;
 870                 ip->ip_v = IPVERSION;
 871                 ip->ip_hl = 5;
 872                 m->m_len -= optlen;
 873                 if (m->m_flags & M_PKTHDR)
 874                         m->m_pkthdr.len -= optlen;
 875                 optlen += sizeof(struct ip);
 876                 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
 877                          (unsigned)(m->m_len - sizeof(struct ip)));
 878         }
 879         m_tag_delete_nonpersistent(m);
 880         m->m_flags &= ~(M_BCAST|M_MCAST);
 881         icmp_send(m, opts);
 882 done:
 883         if (opts)
 884                 (void)m_free(opts);
 885 }
 886
 887 /*
 888  * Send an icmp packet back to the ip level,
 889  * after supplying a checksum.
 890  */
 891 static void
 892 icmp_send(struct mbuf *m, struct mbuf *opts)
 893 {
 894         register struct ip *ip = mtod(m, struct ip *);
 895         register int hlen;
 896         register struct icmp *icp;
 897
 898         hlen = ip->ip_hl << 2;
 899         m->m_data += hlen;
 900         m->m_len -= hlen;
 901         icp = mtod(m, struct icmp *);
 902         icp->icmp_cksum = 0;
 903         icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
 904         m->m_data -= hlen;
 905         m->m_len += hlen;
 906         m->m_pkthdr.rcvif = (struct ifnet *)0;
 907 #ifdef ICMPPRINTFS
 908         if (icmpprintfs) {
 909                 char buf[4 * sizeof "123"];
 910                 strcpy(buf, inet_ntoa(ip->ip_dst));
 911                 printf("icmp_send dst %s src %s\n",
 912                        buf, inet_ntoa(ip->ip_src));
 913         }
 914 #endif
 915         (void) ip_output(m, opts, NULL, 0, NULL, NULL);
 916 }
 917
 918 /*
 919  * Return milliseconds since 00:00 GMT in network format.
 920  */
 921 uint32_t
 922 iptime(void)
 923 {
 924         struct timeval atv;
 925         u_long t;
 926
 927         getmicrotime(&atv);
 928         t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
 929         return (htonl(t));
 930 }
 931
 932 /*
 933  * Return the next larger or smaller MTU plateau (table from RFC 1191)
 934  * given current value MTU.  If DIR is less than zero, a larger plateau
 935  * is returned; otherwise, a smaller value is returned.
 936  */
 937 int
 938 ip_next_mtu(int mtu, int dir)
 939 {
 940         static int mtutab[] = {
 941                 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
 942                 296, 68, 0
 943         };
 944         int i, size;
 945
 946         size = (sizeof mtutab) / (sizeof mtutab[0]);
 947         if (dir >= 0) {
 948                 for (i = 0; i < size; i++)
 949                         if (mtu > mtutab[i])
 950                                 return mtutab[i];
 951         } else {
 952                 for (i = size - 1; i >= 0; i--)
 953                         if (mtu < mtutab[i])
 954                                 return mtutab[i];
 955                 if (mtu == mtutab[0])
 956                         return mtutab[0];
 957         }
 958         return 0;
 959 }
 960 #endif /* INET */
 961
 962
 963 /*
 964  * badport_bandlim() - check for ICMP bandwidth limit
 965  *
 966  *      Return 0 if it is ok to send an ICMP error response, -1 if we have
 967  *      hit our bandwidth limit and it is not ok.
 968  *
 969  *      If icmplim is <= 0, the feature is disabled and 0 is returned.
 970  *
 971  *      For now we separate the TCP and UDP subsystems w/ different 'which'
 972  *      values.  We may eventually remove this separation (and simplify the
 973  *      code further).
 974  *
 975  *      Note that the printing of the error message is delayed so we can
 976  *      properly print the icmp error rate that the system was trying to do
 977  *      (i.e. 22000/100 pps, etc...).  This can cause long delays in printing
 978  *      the 'final' error, but it doesn't make sense to solve the printing
 979  *      delay with more complex code.
 980  */
 981
 982 int
 983 badport_bandlim(int which)
 984 {
 985
 986 #define N(a)    (sizeof (a) / sizeof (a[0]))
 987         static struct rate {
 988                 const char      *type;
 989                 struct timeval  lasttime;
 990                 int             curpps;
 991         } rates[BANDLIM_MAX+1] = {
 992                 { "icmp unreach response" },
 993                 { "icmp ping response" },
 994                 { "icmp tstamp response" },
 995                 { "closed port RST response" },
 996                 { "open port RST response" },
 997                 { "icmp6 unreach response" },
 998                 { "sctp ootb response" }
 999         };
1000
1001         /*
1002          * Return ok status if feature disabled or argument out of range.
1003          */
1004         if (V_icmplim > 0 && (u_int) which < N(rates)) {
1005                 struct rate *r = &rates[which];
1006                 int opps = r->curpps;
1007
1008                 if (!ppsratecheck(&r->lasttime, &r->curpps, V_icmplim))
1009                         return -1;      /* discard packet */
1010                 /*
1011                  * If we've dropped below the threshold after having
1012                  * rate-limited traffic print the message.  This preserves
1013                  * the previous behaviour at the expense of added complexity.
1014                  */
1015                 if (V_icmplim_output && opps > V_icmplim)
1016                         log(LOG_NOTICE, "Limiting %s from %d to %d packets/sec\n",
1017                                 r->type, opps, V_icmplim);
1018         }
1019         return 0;                       /* okay to send packet */
1020 #undef N
1021 }